DEFAULT WEB SITE/ARCGIS/REST HTTP Error 500.0 - Internal Server Error

[PragneshPatel]

I have enabled security on services on my 9.3.1 arcgis server.
and getting this error.
I have tried all the solutions mentioned in thread
I did Post Install, i tried creating new instance from AddInstance.exe but still no luck.
Can anyone help?

[ATTACH=CONFIG]15764[/ATTACH]